Lisa Jarvis

We Need to Build a Better Flu Shot

It’s the time of year when US public health officials are practically begging people to go out and get a flu vaccine. This year, their message is particularly urgent: Protect yourself now because the country might be in for a bad flu season that coincides with a resurgence in Covid cases.

Last week, I took their advice and got my shot (and my Covid booster at the same time). But I’m likely to be in the minority. A recent survey by the National Foundation for Infectious Diseases gauging flu vaccine attitudes in the US found that just 49% of Americans planned to get immunized this year. When people were asked why they were skipping out on the shot, 41% said they didn’t think flu vaccines worked very well.

Maybe it’s time for better vaccines, then. Flu vaccines that offer better, broader and longer-lasting protection might meaningfully bump up the vaccination rate and, in turn, significantly lower the burden of the virus.

The current vaccines still have merit. Even in a year where effectiveness of the shot is low, the Centers for Disease Control and Prevention credits flu vaccines with avoiding millions of illnesses and doctor’s visits, averting tens of thousands of hospitalizations, and saving thousands of lives.

Still, the flu vaccine’s effectiveness is notoriously uneven from year to year. (Effectiveness measures how well the shots can prevent a doctor’s visit, hospitalization, or death.) Because of the lengthy manufacturing process, public health authorities have to make a call on the composition of the vaccine months before people start rolling up their sleeves. The Food and Drug Administration, for example, picked the strains included in this year’s vaccine back in early March. That means some years the predictions of which viruses will circulate are better than others. The range of protection spans anywhere from over 60% to below 20%.

If that effectiveness were more reliably high, maybe more people would be motivated to get their shots. The good news is that after a decades-long struggle to improve the flu vaccine, followed by delays in clinical trials during the pandemic, the next few years could bring more options.

Progress will likely come in waves, initially with seasonal vaccines that align better with circulating flu viruses. Eventually, if all goes well, we might see so-called universal vaccines.

That potential first wave of better seasonal vaccines relies on the mRNA technology that brought us our Covid vaccines and boosters. Development of these vaccines began well before the pandemic. Moderna and Pfizer/BioNTech both are working on shots that carry recipes for building four versions of a flu protein called hemagglutinin — one for each strain included in the traditional flu vaccine.

The advantage of mRNA is speed. Moderna and Pfizer/BioNTech need less time to design, manufacture and distribute an mRNA flu vaccine than to produce the traditional version. In theory, this means they can make a more accurate choice about the composition of the annual shot, resulting in a more consistently effective vaccine.

Of course, both companies still need to show how well their mRNA vaccines stack up against conventional flu vaccines. That’s an open question. Both companies recently started large, late-stage studies of flu shots.

Both are also already pursuing next-generation mRNA flu vaccines that might improve upon this first round. Moderna, for example, is working on shots that include the recipe for two flu proteins. And Pfizer has said that it is exploring the potential of a self-copying mRNA technology that, as I’ve explained in the past, could allow for much smaller doses and is easier to store and distribute.

The more distant wave that many researchers hope would be a game changer in flu is the arrival of universal vaccines. That term “universal” has become a catchall for a lot of different types of vaccines, including ones that could protect against all strains of a particular subtype (say, every variation on H1N1); ones that protect against all strains of a particular flu (say, influenza A, which is responsible for the majority of infections); and shots that could protect against all past, current and future strains of all types of flu (a much harder problem).

Because these vaccines would in theory work against whatever types of flu ended up in circulation, they wouldn’t need to be updated from year to year. That could make them less expensive to manufacture, and some researchers hope they might even open the door to less frequent vaccination. Unfortunately, these universal vaccines are also in the earliest stages of testing.

If any of these new generations of flu vaccines turns out to work, hopefully people let go of their excuses and line up for one. For now, with CDC data showing flu cases in the US are already ticking upward, everyone should consider getting the shots we already have. They might not be perfect, but they work well enough to save many lives.